Novel Fin-Shaped Drift SOI LDMOS Featuring Drift-All-Around Electron Accumulation Effect

This letter proposes a novel lateral double-diffused MOSFET based on a silicon-on-insulator (SOI) structure with a drift-all-around electron accumulation layer (EAL) (DAA-LDMOS). The DAA structure incorporates a self-adaptive potential region (SAP) surrounding a fin-shaped drift region, and a control electrode atop the SAP region. The potential existing in the SAP region and buried oxide (BOX) layer is perpetually higher than in the drift region, maintaining an unwavering potential differential, which introduces a 3D fully enclosed rectangular EAL in the drift region. Moreover, a control electrode can deftly modulate the intensity of the EAL to achieve the optimal accumulation effect. Consequently, the device possesses an extremely wide current path with ultralow resistance, dramatically decreasing the specific ON-resistance R ${}_{\mathbf {\textit {ON},\textit {sp}}}$ . The simulation results show that the ${R} _{\mathbf {\textit {ON},\textit {sp}}}$ of the DAA-LDMOS was reduced from 12.56m $\Omega $ cm ${}^{\mathbf {{2}}}$ of the conventional LDMOS (Cov. LDMOS) without accumulation effect to 0.28 m $\Omega $ cm ${}^{\mathbf {{2}}}$ , a reduction of 97.7% at the same breakdown voltage BV of 260 V. The figure-of-merit (FOM) of the DAA-LDMOS increased from 5.5 MW/cm ${}^{\mathbf {{2}}}$ of the Cov. LDMOS to a record high of 237.7 MW/cm ${}^{\mathbf {{2}}}$ , demonstrating an exceptional performance.